Bolton gave their promotion hopes a boost with a 1-0 win at Oxford thanks to an early strike from Dion Charles.
It was just the Trotters’ second victory in seven league games, while a first defeat under new boss Liam Manning means Oxford are above the relegation places only on goal difference.
Wanderers had the perfect start when Northern Ireland international Charles followed up to score from 10 yards in the seventh minute.
Simon Eastwood could only parry Conor Bradley’s cutback from the right and the ball ran invitingly for Charles to bag his 22nd goal for club and country this season.
Oxford, looking for a first win in 15 games, were bereft of confidence and kept giving the ball away in the first 30 minutes.
There was controversy before half-time when Oxford forward Kyle Joseph, in a race for the ball, was taken out by keeper Brandon Fleming outside the area.
Ref Sebastian Stockbridge showed Fleming a yellow card when home fans were calling for red.
Oxford improved in the second half but could not find an equaliser, Joseph and Marcus Browne drilling efforts off target.